This invention relates to a cerium yttrium magnesium aluminate fluorescent lamp phosphor possessing the hexagonal magneto plumbite structure and to fluorescent lamps incorporating the phosphor.
Philips Electronics and Associated Industries in British Pat. No. 1,452,083 disclosed an ultraviolet emitting fluorescent lamp phosphor having the composition CeMgAl.sub.11 O.sub.19 and the magneto plumbite structure. H.F. Ward of Thorn Industries, in British Patent 1,194,014 disclosed a phosphor having the composition CeAl.sub.11 O.sub.18 and the magnetoplumbite structure. Although CeAl.sub.11 O.sub.18 and CeMgAl.sub.11 O.sub.19 have similar crystal structures, incorporation of magnesium shifts the UV excited emission peak from about 460 nm in CeAl.sub.11 O.sub.19 to about 370 nm in CeMgAl.sub.11 O.sub.19. These phosphors are self-activated by the Ce.sup.3 + ion.